Star data networks with logical ring function utilizing token access have been well known for ten years. An exhaustive description of the concept and its realization with the aid of line concentrators was published in 1983 in IBM systems Journal vol 22, nos 1/2, by R. C. Dixon, N. C. Strole and J. D. Markow.
Embodiments known up to now of data network with logical ring function usually have the disadvantage of requiring new lines for achieving satisfactory function. This means that large earlier investments in terminal networks with coaxial cables cannot be utilized in such embodiments.